The invention relates to scalable peer-to-peer networks.
With known scalable networks, that is networks on which there are no restrictions as regards the number of peers, such as Napster, Gnutella, Freenet, etc. peers, that is computers, can log on, search for files among all registered peers and/or release their own files for access by other computers (known as file sharing).
In this case, with centrally-biased peer-to-peer networks, peers are logged on with one or more central servers and files which are to be released by the peers are registered with a directory service running on a server.
To search for a specific file a peer puts in a specific search request to the server which then sends it a list of peers (directory service), that have ‘released’ this file. The searching peer can then select one of these peers and request or download the file directly from this peer.
A disadvantage of these centrally biased peer-to-peer networks, such as Napster, iMesh, Audiogalaxy, Songspy etc. for example, is that they depend on the availability of a central server, without which the directory service and thereby the logon, registration and search for released files do not function.
Furthermore decentralized peer-to-peer-networks exists without central servers for a directory service. In such networks a peer dynamically discovers other peers in networks and communicates with them in order to exchange files and information. Advantageously the function and availability of such a decentralized network does not depend on the function and availability of a central server. However the peers must find each other by themselves. This generally only happens within a specific local area (e.g. using IP multicasting with a maximum hop count) or by using a list of previously known peers, which is created manually or is requested by specific servers.
A decentralized peer-to-peer-network additionally requires a self-contained routing protocol with which the file is routed via various peers. To search for a file a peer transfers its search request to the peers known to it, which also behave in the same way. In this way the entire network (all peers) is flooded with the search request and each peer which has released a file corresponding to the search request notifies this to the peer initiating the search. The peer conducting the search can then select one of these peers and request the file directly from them.
Such decentralized peer-to-peer-networks, for example Gnutella, KaZaA, Freenet, MojoNation, Edonkey2000, etc. do not offer a directory service, that is there are no lists that can be retrieved from the network with information about the released files. Disadvantageously searches in these types of decentralized peer-to-peer-networks, because of the need to flood the entire network with requests, are comparatively time-intensive and ineffective.